In order to start an automobile, a key is inserted into an ignition switch, and then the key is turned. As a result, a state of the automobile is changed, causing an engine to start. At this time, if the key is stolen, if the lock is picked or in other similar cases, there is a possibility that the automobile will be driven by a malicious person or other non-owner of the automobile. A method for starting an automobile having an immobilizer function is described in Japanese Patent Laid-open No. 2000-108848. According to this method, only a key in which an IC called a transponder is embedded can start an engine, which prevents lock picking, or use of a copied key. In addition, a method for authenticating an individual, which uses a finger-vein pattern as biological information in order to increase security, is described in Japanese Patent Laid-open No. authentication of an individual using biological information and a key switch are combined is described in Japanese Patent Laid-open No. 2000-352245.